Abstract base class for TokenFilters that may remove tokens.
You have to implement accept() and return a boolean if the current
token should be preserved. incrementToken() uses this method
to decide if a token should be passed to the caller.

incrementToken

Consumers (i.e., IndexWriter) use this method to advance the stream to
the next token. Implementing classes must implement this method and update
the appropriate AttributeImpls with the attributes of the next
token.

The producer must make no assumptions about the attributes after the method
has been returned: the caller may arbitrarily change it. If the producer
needs to preserve the state for subsequent calls, it can use
AttributeSource.captureState() to create a copy of the current attribute state.

To ensure that filters and consumers know which attributes are available,
the attributes must be added during instantiation. Filters and consumers
are not required to check for availability of attributes in
TokenStream.incrementToken().

getEnablePositionIncrements

setEnablePositionIncrements

public void setEnablePositionIncrements(boolean enable)

If true, this TokenFilter will preserve
positions of the incoming tokens (ie, accumulate and
set position increments of the removed tokens).
Generally, true is best as it does not
lose information (positions of the original tokens)
during indexing.

When set, when a token is stopped
(omitted), the position increment of the following
token is incremented.